HARTFORD -- Bridgeport's controversial coal-burning power plant would have its emissions testing cut to just once a year under legislation unanimously approved Wednesday in the state Senate.

Lawmakers and state environmental officials said the 401-megawatt plant, which is only used part time, has easily passed the four emissions tests a year it's now required to have. Often, it is fired up just so the Department of Energy and Environmental Protection can perform the tests, they said.

But an official from the Sierra Club, which contends the power plant spews pollution and greenhouse gases, said Connecticut should make plans for closing the Bridgeport Harbor Station, rather than giving it reprieves from the current emissions surveys.

"As long as the Bridgeport coal plant remains in operation, it poses a health and safety threat to the people of Bridgeport," said Onte Johnson, organizing representative for the Sierra Club's Beyond Coal Campaign. "This is not the time to scale back inspections. Instead, we think they should help retire the plant and find ways to make up for tax revenue and community assistance programs for the plant's post-retirement."

Under the bill, which next moves to the House, a failure of a future test at the power plant would result in a return of the quarterly emissions checks of the facility, owned by PSEG Power Connecticut LLC.

Sen. Ed Meyer, D-Guilford, co-chairman of the Environment Committee, said the facility, which burns natural gas and oil in addition to coal, has routinely passed inspections for years.

"By reducing it to once a year, that will save this company millions of dollars that will hopefully be passed on to consumers," Meyer said during the brief floor debate.

The plant, which came on line in 1967 and is the last coal-fired power facility in the state, can supply electricity to nearly 530,000 homes when running at full capacity. Last year, the Bridgeport Harbor plant operated about 6 percent of the time, for a total of 561 hours, said Dennis Schain, spokesman for the DEEP.

"We were comfortable with the bill because emissions-testing programs are generally annual," Schain said in a phone interview, stressing that it has regularly been in compliance with emission standards.

It often gets started just so DEEP inspectors can measure emissions, said Sen. Clark J. Chapin, R-New Milford.

"We're actually helping air quality by not requiring the test," he said.

Lee Gray, spokesman for PSEG Power CT, said Wednesday that the harbor generator is a so-called peaking facility, which only comes on line when ordered to by the regional power authority at times when more electricity is needed.

The plant property is the third-highest taxpayer in the city, assessed at more than $122 million.

Johnson, of the Sierra Club, said while the Bridgeport plant doesn't operate often, when it does run -- often in the depths of the summer -- it causes concerns.

"Running it on the hottest, smoggiest days doesn't help with air quality or help against global warming," Johnson said.